1. Field of the Invention
The present invention relates to the content delivery utilizing Internet Protocol (1P) networking, particularly, although not exclusively data networks.
2. Description of the Prior Art
Wireless IP networks, and particularly mobile wireless IP networks typically include a terminal having stringent power requirements. Such a mobile terminal may be required to operate for lengthy periods on an internal source of power. In the case of simplex wireless IP networks exemplified by the Digital Video Broadcast (DVB) terrestrial (DVB-T) and satellite (DVB-S) networks, typically a large part of the energy requirement of a terminal is due to the demands of a receiver necessary to receive transmissions carrying a range of content.
It is the case, however, that a user of the terminal may at an application level, as set out in the well-known Open System Interconnect (OSI) model, make a selection of particular content from the range of content presently received by the terminal. Although such a selection may take place in a unicast environment, that is a one to one transmission, more typically the content is distributed in a one to many transmission, that is a multicast environment.
A well-known mechanism for facilitating the delivery of content in a multicast environment is provided by the Session Announcement Protocol (SAP), details of which are set out in RFC2974 published by the Internet Engineering Task Force (IETF repository at http://www.ietf.org) and the Session Description Protocol (SDP), details of which are to be found in RFC2327 published by the Internet Engineering Task Force (IETF repository at http://www.ietf.org) which are incorporated herein by reference in their entirety. In summary, an Application Programming Interlace (API) is provided which facilitates communication between applications over an IP protocol. The API listens at a particular address for information identifying available streams of content, so-called services. The information provided at that address is then provided to an application, a browser for example, which in turn uses the API to access a selected stream by opening a socket at which the selected stream can be heard. Typically, the selection of the desired content is made by a user via the browser, i.e. by clicking on a particular link.